Motor fuel composition containing a halocarbon compound



United States Patent M 3,246,965 MOTOR FUEL COMPOSITION CONTAINING A HALOCARBON COMPOUND Philip S. Fay, Lyndhurst, and Fred J. Fox, Euclid, Ohio, assignors to The Standard Oil Company, Cleveland, Ohio, a corporation of Ohio No Drawing. Filed Dec. 24, 1958, Ser. No. 782,641 4 Claims. (Cl. 44-69) This invention relates to improved motor fuel compositions, particularly leaded fuel compositions for use in internal combustion engines, to modify combustion chamber deposits within the engine so as to alleviate engine knock and roughness normally resulting from uncontrolled fuel ignition. More particularly, this invention relates to ga-solines containing small amounts of halocarbon compounds which are effective in modifying the action of the fuel in the engine through the alteration of the amount or natureof the deposits therein so as to reduce the tendency of said gasolines to pre-ignite in an engine.

It is intended that the motor fuel of this invention will contain appreciable amounts of tetraethyl lead and also may include other known additives found in commercial fuels today, such as oxidation inhibitors, gum inhibitors, dyes, solvents, boron compounds, and the like. The base gasoline used in the present invention can comprise a mixture of hydrocarbons boiling in the gasoline range and can be either a straight-run gasoline or a gasoline obtained from a conventional cracking process, or mixtures thereof. The base gasoline may also contain components obtained from the various other refinery processe ssuch as alkylation, isomerization, hydrogenation, polymerization, catalytic reforming, or combinations of tWo or more of such processes.

It is Well known that during the operation of an initially clean internal combustion engine on gasoline-type fuels that deposits form progressively and accumulate on the surfaces within the combustion zone, i.e., on the cylinder head, piston top, sparkplug, and the intake and exhaust valves. gravated when tetraethyl lead is contained in the fuel for the purpose of economically increasing the octane number of the fuel to a desired level for modern high compression engines. The use of leaded fuels leaves combustion chamber deposits which are no longer essentially carbonaceous in chemical nature, but comprise appreciable quantities of lead compounds generally mixed in the carbonaceous material. The fact that such deposits are partially metallic in character is believed to give it a catalytic activity which modifies the action of the deposit in affecting engine operation. Despite the fact that one or more volatile organic halides such as ethylene dichloride and/or ethylene dibromide are included in the fuel as scavenging agents, not all of the lead is removed.

Combustion chamber deposits and particularly deposits resulting from the burning of leaded fuels exhibit a number of adverse effects upon engine operation. One of these adverse effects which represents a major problem in automotive engines and reciprocating-type aircraft engines is characterized by uncontrolled ignition, either preignition or post-ignition. This is explained by the fact that these deposits or portions of them become heated to incandescence and ignite the air-fuel mixture either before or after the portion in the cycle at Which the charge would be ignited by the spark from the sparkplug. This manifests itself in various ways, characterized as roughness, rumble, and a general lack of smoothness in engine operation. This is not to be confused with the knocking that is a function of the octane rating of a fuel.

It has been discovered in accordance with this invention This deposit problem is particularly tag 1 Patented Apr. 19, 1966 that a motor fuel, and particularly leaded gasoline, can be improved with respect to its tendency toward uncontrolled ignition in an engine by incorporating in the fuel a small amount of at least one fluorine-containing 'halocarbon compound of the group consisting of 1,1- .difiuoro 2,2-dichloroethane -(F HC-CHCl 1-fluoro--l,2, Z-trichloroethane (FCIHO-CHCI and 1,1,1-trifiuoro-2, 3,3-trichloro-2-propene (F C-CCl=CCl The above compounds are well known to the art and are commercially available from various sources of supply, and hence it is unnecessary herein to discuss in further detail the preparation of these compounds. Although it will be noted that all of the compounds which are suitable for the purposes of the invention are fluorine-containing, there appears to be no correlation between the structure of these fluorine-containing compounds and their effect on surface ignition. For example, other closely related compounds such as 1,1,2-trifiuoro-l,2,2-trichloroethane F ClCCFCl and l,1-difiuoro-2,3-dichloro-2-propene are found to be ineffective for purposes of the invention. Therefore, this invention is based, at least in part, on the discovery of the specific group of fluorine-containing halocarbon compounds which respond in a gasoline to alleviate pre-ignition of said gasoline in an internal combustion engine.

The amount of fluorine-containing halocarbon compound which is incorporated in the fuel depends in part upon the particular fuel employed. In general, the amount is based upon that amount theoretically required to convert the lead introduced into the fuel in the form of tetraethyl lead to lead fluoride. Amounts corresponding to at least about 0.5 times to 2.0 times that theoretically required may be used, and amounts corresponding to 1.0 times to 1.5 times that theoretically required is particularly desirable. Amounts greater than 2 times the theoretical amount can be employed, but for economic reasons it is preferred to'use only the amounts stated above.

Therefore, in view of the fact that the amount of tetraet'nyl lead in gasoline varies from one fuel to another, it is difficult to state on a weight basis the amount of halocarbon compound based upon the weight of gasoline. However, once the amount of tetraethyl lead in the gaso line is known, it is an easy matter to calculate the amount of the desired halocarbon required. For example, in commercial practice today it is common to use approximately 3 cc. of tetraethyl lead per gallon of base gasoline fuel and on this basis it may be readily'determined that the amount of 1,1-difluoro-2,2-dichloroethane required in accordance with this invention to provide the desired concentration recited hereinabove is between 0.075 and 0.113% by weight based on the weight of the gasoline. The halocarbon compounds suitable for the present invention, when added to leaded gasoline in the amounts preferred, may also serve to replace in whole or in part the ethylene halides, such as ethylene dibromide or ethylene dichloride, or mixtures thereof, which are normally incorporated in fuels in an effort to scavenge the lead deposit-s from the combustion chambers of an engine, thereby favorably affecting the economics of using these compounds. However, it is to be understood that these fluorine-containing halocarbon compounds can be used in conjunction with the usual amount of alkyl halide scavenging agent without dcleteriously affecting the beneficial effects of these compounds.

The halocarbon compounds of this invention may be readily blended into the leaded gasoline. They may be added directly to the gasoline or, if preferred, a gasoline concentrate thereof may be formed and the concentrate thereafter may be added to the fuel. A still further method of introducing these compounds into the base fuel is through the use of an alcohol or any other mutual solvent which will not adversely affect the desirable .properties of thefuel. w

A better understanding of the nature and scope of the present invention will be gained from the following working examples. To determine the efiectivenessof the gasolines of the invent-ion in suppressing surface ignition, an ASTM-CPR single-cylinder engine having the compression ratio adjusted at 12:1 was employed. Preparatory to the test cycle, the engine was run open throttle at 900 r.p.m. for thirty minutes to stabilize the engine conditions for the test period. Following this, the engine was run at open throttle continuously under the following conditions:

Speed r.p.m 900 Spark advance degrees Airzfuel ratio 13:1

for three hours, during which time the total surface ignition count and audible surface ignition count were observed electronically. All experimental conditions were the same for each test except the fuel composition.

The base gasoline in each test was the same and had the following composition and specifications.

Light naphtha 7.50 Catalytic distillate 25.0 Catalytic reformate 63.5 Isopentane 4.0 Tetraethyl lead mL/gal. 3.10 Engler distillation:

IB'P 108 10% 139 30 190 50 246 70 300 90 374 95 428 EP 438 The number of surface ignitions in the various test fuels is expressed as a percentage of the surface ignitions of the base gasoline with the results of the above test being as follows:

It will be noted from the data in Table I above that the engine operating on fuel compositions 2, 3, and 4, which are fuels of the present invention, exhibit significant 1 gasoline.

reductions in total surface ignition counts over the base These same fuels, with the exception of only fuel composition 4, also demonstrate significant reductions in audible surface ignition counts over the base gasoline. By contrast, it will be not-ed that fuel composition 5, which represents a gasoline incorporating a halocarbon compound closely related to the halocarbon compounds which are suitable for the invention, demonstrates an adverse effect on total and audible surface ignition countsrelative to the rating of the base gasoline.

We claim:

1. A gasoline for use in internal combustion engines containing appreciable amounts up to 3 cc. of tetraethyl lead I per gallon and a fluorine-containing halocarbon compound selected from the group consisting of 1,1- difluoro 2,2 dichloroethane; 1 fluoro 1,2,2 trichloroethane; and 1,1,1-trifluoro-2,3,3-trichloro-2-propene in an amount at least 0.5 times to 2.0 times the theoretical amount thereof required to convert the lead to lead fluoride.

2. A gasoline for use in internal combustion engines containing appreciable amounts up to 3 cc. of tetraethyl lead per gallon and an amount of 1,1-difiuoro-2,2- dichloroethane which is at least 0.5 times to 2.0 times the theoretical amount thereof required to convert the lead to lead fluoride.

3. A gasoline for use in internal combustion engines containing appreciable amounts up to 3 cc. of tetraethyl lead per gallon and an amount of 1-fluoro-1,2,2- trichloroethane which is at least 0.5 times to 2.0 times the theoretical amount thereof required to convert the lead to lead fluoride.

4. A gasoline for use in internal combustion engines containing appreciable amounts up to 3 cc. of tetraethyl lead per gallon and an amount of 1,1,1-trifluoro- 2,3,3-trichloro-2 propene which is at least 0.5 times to 2.0 times the theoretical amount thereof required to convert the lead to lead fluoride.

References Cited by the Examiner UNITED STATES PATENTS 1,668,022 5/1928 Midgley 4469 2,214,768 9/1940 Lincoln 4479 2,281,598 5/ 1942 Prutton 4479 2,364,921 12/1944 Shokal 4479 2,479,900 8/ 1949 Calingaert 4469 2,490,606 12/1949' Williams et al. 4469 2,573,579 10/1951 Lacomble 4469 2,794,160 3/1957 Blaker 4479 2,822,252 2/1958 Boag et a1. 4469 2,838,387 6/1958 Rudel 4479 2,937,932 5/1960 Newman et al. 4479 FOREIGN PATENTS 761,223 11/1956 Great Britain. 804,763 11/ 1958 Great Britain.

DANIEL- E. WYMAN, Primary Examiner. JULIUS GREENWALD, Examiner. 

1. A GASOLINE FOR USE IN INTERNAL COMBUSTION ENGINES CONTAINING APPRECIABLE AMOUNTS UP TO 3 CC. OF TETRAETHYL LEAD PER GALLON AND A FLUORINE-CONTAINING HALOCARBON COMPOUND SELECTED FROM THE GROUP CONSISTING OF 1,1DIFLUORO-2,2-DICHLOROETHANE; 1-FLUORO-1,2,2,-TRICHLOROETHANE; AND 1,1,1-TRIFLUORO-2,3,3-TRICHLORO-2-PROPENE IN AN AMOUNT OF LEAST 0.5 TIMES TO 2.0 TIMES THE THEORETICAL AMOUNT THEREOF REQUIRED TO CONVERT THE LEAD TO LEAD FLUORIDE. 